A known connection device for use in osteosynthetic external fixation systems comprises on the one hand two gripping jaws and a screw that goes through them, and on the other hand a loop connected with said screw, a U-shaped counterpart that envelops the loop, and a screw that goes through this counterpart and is attached to the loop. Advantageously, this connection device is attached to, for example, a Schanze entrenchment screw, by means of the gripping jaws, while a rod, for example a carbon filament rod, can be secured to the opposing segment of the connection device. The carbon filament rod is positioned approximately parallel to the broken bone to be treated and is connected via several of said connection devices with Schanze screws screwed into the bone on both sides at the fracture; the desired external setting of the bone is thereby achieved. It is very important that the connection device be very easy to handle and that a very rigid setting be achieved without excessive expenditure of force, so that in case of shocks or other outside influences the bone parts will not shift in relation to each other and so that even after the passage of time the setting will retain its rigidity. In the known connection device described, experience has shown that over an extended period of time the tension in the setting device can slacken somewhat, and leading to conditions not always optimum.